Master pattern for producing cast raised figures

ABSTRACT

A master pattern for the casting of raised figures such as lettering on a plaque or plate is produced by hobbing the figures into a material which has been pre-formed with suitable void or open spaces to accommodate the material displaced during hobbing.

United States Patet Camilleri *July 8, 1975 MASTER PATTERN FOR PRODUCING CAST RAISED FIGURES [56] References Cited [76] Inventor: Thomas M. Camilleri, 277 Avenue UNITED STATES PATENTS West, Brooklyn, N.Y. 11223 991,747 5/1911 Rawsthome 76/107 R Notice: The portion of the term of this patent subsequent to July 24 1990, Primary Exammer-L. Dewayne Rutledge has been disclaimed Assistant ExaminerO. F. Crutchfield Attorney, Agent, or Firm-Zarley, McKee, Thomte & [22] Filed: June 11, 1973 Voorhees [21] App]. No.: 368,642 [57] ABSTRACT Related Apphcatmn Data A master pattern for the casting of raised figures such [62] DlVlSlOl'l of Ser. No. 186,690, Oct. 5, 1971, Pat. No. as lettering on a plaque or plate is produced by bing the figures into a material which has been preformed with suitable void or open spaces to accommos s e 1 e a I I s s v e s [58] Field of Search 29/183 1 Claim, 11 Drawing Figures SHEET FIGZ FIG. 3

SHEET FIG. 5

FIG 7 SHEET W7WW//// F IG. 8

FIG. IO

MASTER PATTERN FOR PRODUCING CAST RAISED FIGURES This is a divisional application of application Ser. No.

186,690, filed Oct. 5, 1971 now US. Pat. No. 3,747,440.

BACKGROUND AND SUMMARY OF THE INVENTION This invention relates to the casting of raised figures such as lettering on metal surfaces or other material, and more particularly to a method wherein a negative master is produced by hobbing.

Heretofore, the casting of raised figures such as lettering found on plaques and plates has required the use of a master pattern produced by engraving. The engraving procedure is a long and costly one requiring skilled and trained craftsmen. It has been the experience that the casting process for producing raised figures is only feasible in situations calling for the production of items in mass quantities where the initial outlay of cost for skilled engraving can be readily absorbed. Where such was not the case, the cost of engraving became exorbitant.

In situations where casting has heretofore not been feasible, embossing, indented, or scratch letter, (approximately 0.003 inch depth) processes have been employed. Embossing, indented, and scratch lettering are suitable only in connection with sheet materials and all three procedures are qualitatively not as desirable as casted raised letters in terms of the end product produced.

The hobbing technique has been tried as a means for implementing the casting of raised letters, but in the past has produced wholly unsatisfactory results in plaque or plate lettering and similar situations requiring accuracy and uniformity in the figures. Distortion in the lettering has invariably resulted. The pressure applied during the hobbing step results in the hobbed material being displaced upwardly and inwardly distorting and deforming the lettering produced.

It is an object of the present invention to provide a method for producing raised lettering by casting which will render the casting procedure competitive with all other techniques regardless of the number or quantity of articles to be produced. More particularly, it is an object of the invention to provide a method for producing a negative master for casting by the technique of hobbing in lieu of engraving whereby qualitative results comparable to engraving are achieved.

Briefly and generally, the foregoing and other objects, features and advantages which will become apparent herefrom are achieved in accordance with the invention by a method in which the material to be hobbed is first preformed with a suitable distribution of void or open spaces, preferably on the surface as by knurling, to accommodate the flow of material displaced by the imprint formed during hobbing. In accordance with a further principle of the invention, the accommodating voids must have a volume in the region to be occupied by the lettering and a peripheral region extending outwardly therefrom a distance equal to the thickness of the material being hobbed at least equal to the volume of imprint to be formed. The resultant negative imprint in the master is free of all distortion and constitutes an exact mirror image of the letters to be cast.

BRIEF DESCRIPTION OF DRAWINGS Having summarized the invention, there follows a detailed description thereof with reference to the accompanying drawings forming part of the specification, of which:

FIG. 1 is a perspective view, partially in section, diagrammatically illustrating a knurling apparatus constituting the presently preferred means by which suitable accommodating voids are produced in a master workpiece in accordance with the invention;

FIG. 2 is a sectional view diagrammatically illustrating the apparatus of FIG. 1 closed in the process of knurling the workpiece surface in accordance with one embodiment of the invention;

FIG. 3 is a view similar to FIG. 1 diagrammatically illustrating the distribution of surface voids produced by knurling pursuant to the procedure illustrated in FIG. 2;

FIG. 4 is a view similar to FIG. 1 diagrammatically illustrating apparatus for impressing a negative or mirror-image imprint of raised letter forms on the knurled workpiece surface in accordance with the invention;

FIG. 5 is an enlarged fragmentary sectional view taken on line 55 of FIG. 4 illustrating in detail the surface voids formed therein by knurling;

FIG. 6 is a view similar to FIG. 2 in which the raised letter forms are being hobbed or impressed into the knurled surface in accordance with the invention by the apparatus of FIG. 4;

'FIG. 7 is a view similar to FIG. 3 illustrating the negative or mirror-image imprint of the raised letter forms hobbed in the knurled surface pursuant to the step of FIG. 6;

FIG. 8 is a sectional view taken on line 8-8 of FIG. 7 further diagrammatically illustrating the mirrorimage imprint of the raised lettering formed in the knurled surface;

FIG. 9 is a diagrammatical view illustrating the final step of the improved casting process of the invention in which the negatively imprinted master of FIG. 8 is placed in a die-casting apparatus;

' FIG. 10 is a diagram illustrating the manner in which 'the cri tical knurling area is determined in accordance with-the invention; and

- FIG. 11 is a perspective view of a die-cast plaque having lettering produced in accordance with the invention as illustrated in FIGS. 1-10.

DETAILED DESCRIPTION Turning now to the accompanying drawings in which likereference characters are employed to designate like parts throughout, means are illustrated in FIG. I for forming suitable accommodating voids in accordance with the invention by knurling a workpiece 20 which is to serve as the casting die or master. While surfaceknurling, i.e., the forming of surface depressions, is the presently preferred means for carrying out the invention by virtue of its simplicity, it is contemplated thatgany means by which a suitable void distribution can be formed, either on the surface or in the body of the workpiece, will be satisfactory and useful in the practice of the invention.

As illustrated, the knurling means can conveniently comprise a conventional hydraulic press having a workpiece holder 21 and'a cooperative overhanging press device 22. Suchapparatus is well known in the hobbing 3 art and further description hereinqisunnecessary. A typical knurling tool2 3 is illustrated in FIG. l suitably secured tothe 'press'device andjs'upported thereby directly, abovethetworkpiecel20.

As best shown in FIG. 2,' the vorkpiece "is positioned in a recessedarea or. cavity 24 in the holder 21. The workpiece material, thus coiifined, is prevented from distorting around its perimeter or bottom surface during the knurling step. I

In FIG. 2, the press device 22 is closed on workpiece holder 21 with sufficient force F to impress the surface configuration of knurling tool 23 into the exposed surface of workpiece 20 to the desired depth of knurl. Assuming, for example, that the tool is pressed into the workpiece 0.025 inch, the workpiece material will rise into the openings 'of the knurling tool approximately 0.020 inch". As a result, the workpiece material of the example will hav'e incieased in overall thickness approximately 0.( )20 inch and a series of uniformly spaced bperiingsof voids 25 will have been formed in the workpiecesurfa'ce' as illustrated in FIGS. 3, 4, and

It is believed that a percentage of the material of the workpiece is compressed or compacted during the knurling step, but the rest of the displaced material flows upwardly to increase the overall thickness of the workpiece. The material displaced by the knurling tool where thesurface voids are formed displaces the adjacent material and soon with the increase in thickness approximately equal to the volume of the voids formed. The configuration of the knurling tool and the depth of the knurl is determined by the nature of the figures to be hobbed.

In accordance with a principal of the invention, the voids formed in the material must have a volume at least equal to the volume of figures to be hobbed or imprinted in the workpiece surface, and preferably the volume of the voids should be at least twice as great as the volume of the hobbed figures. V

The l:'1" ratio of voids to hobbed volume represents the critical'minimum below which distortion will begin to occur. The 2:1 ratio provides a safe tolerance to avoid distortion.

As illustrated in FIG. 10, the critical knurling area constitutes the area occupied by the lettering a'ndan additional peripheral region extending a distance from the lettering equal to the thickness of the material. This relationship of material thickness to knurling area pertains regardless of the nature of thematerial itself. It has been found that the material displaced during the hobbing step flows 'ordisplaces downwardly and outwardly at an angle of 45 from the surface. By confining all of the surfaces of the workpiece material except the upper or exposed surface during hobbing', ultimately 55 After a suitable distribution of accommodating voids have been formed as hereinaboved'escribed, the mate-' rial is ready to accept the-figures' tofbe hobbed, illustratively, the letters .I oh'ti"Doe;""Referringito FIG. 4, conventional letter forms"26 spellin'gout the name John Doe are held by the press-deviee 221mm relation f in a'ny suitable manner. As can be seen the letters are arranged as theywoul'd appear i'n'the final product.

As illustrated, in FIG. 6, during the hobbing step the press is closed with sufficient force to impress the le t'ter forms into the knurled surface of workpiece 20 to the desired depth, thereby forming :a'negative or mirrorimage imprint of thename as shown in FIG. 7. The depth of the imprint is equal to the desired height of the raised lettering to be cast. f I It should be observed from'FIGS. and '8 "thatthe surface voids nearest the imprintedletters are ller in size than the voids further away from the lette'rs. During the hobbing step, material 'in the area occupied by the letters becomes displaced' andfiri accordance with the invention, is accepted by the openings 'o rvoids in the knurled surface. Asa result, distortion of the lettering is avoidedI l k A After the press device 22 is opened, the"work'piece 20 havingthe mirror-imaged letters'imp rinted thereon'as in FIG. 8 is placed into a suitable die-casting apparatus 27 where the finished plaque or plate illustrated in FIG. 11 is formed. As illustrated 'in FIG. '11, the lettering constitutes an exact undistorted replica of the name John Doe as in the letter forms 'illustrated'iii FIG. 4. As can clearly 'be seen, the surface of the finished plaque of FIG'. 11 also has formed thereon a distribution of raised surface areas 28 corresponding to the surface voids 25 in the workpiece 20.

' It is to be understood that the present invention is not limited' to knurling as a means for forming suitable voids in the workpiece material. Any other technique providing for the formation of voids'in the bodyof the material or on its surface within the critical area illustrated in FIG. 10 is contemplated by the present'invention. Similarly, it is to be understood that the invention is not limited to'lettering but cari'be used to produce any type or arrangement of raised figures. The present invention has particular utilityand represents a major advance" in connection withlettering or'numbering where standard printers forms can be employed. f I claim: i 1. "The product of a method of producing a mirror image imprint of figures in a metal nonsheet material to serve as a master for the casting of raised figures such as lettering found on plaques and plates which method comprises:

a. forming a plurality of voids in said nonsheet material without removing material in the'surface which is to receive said imprint, said voids being suitable to accommodate" the flow of material to be displaced during the imprinting of said figures and being located both within and without the'areas to be occupied by said imprinted figures;

b. Arranging and securing forms of the figures to be 'cast in fixed relationship corresponding to the raised figures to be produced by castings; and

c. Impressing said forms into said material thereby causing that material in the areas occupied by said forms to be displaced and causing a flow of inaterial into a plurality of said voids to occur to produce in undistorted imprint constituting an exact mirror image replica-of the figures to be ca'st, said plurality of voids which receivesa'id' material including voids located outside'the areas occupied by said figures. 

1. THE PRODUCT OF A METHOD OF PRODUCING A MIRROR IMAGE IMPRINT OF FIGURES IN A METAL NONSHEET MATERIAL TO SERVE AS A MASTER FOR THE CASTING OF RAISED FIGURES SUCH AS LETTERING FOUND ON PLAQUES AND PLATES WHICH METHOD COMPRISES: A. FORMING A PLURALITY OF VOIDS IN SAID NONSHEET MATERIAL WITHOUT REMOVING MATERIAL IN THE SURFACE WHICH IS TO RECEIVE SAID IMPRINT, SAID VOIDS BEING SUITABLE TO ACCOMMODATE THE FLOW OF MATERIAL TO BE DISPLACED DURING THE IMPRINTING OF SAID FIGURES AND BEING LOCATED BOTH WITHIN AND WITHOUT THE AREAS TO BE OCCUPIED BY SAID IMPRINTED FIGURES, B. ARRANGING AND SECURING FORMS OF THE FIGURES TO BE CAST IN FIXED RELATIONSHIP CORRESPONDING TO THE RAISED FIGURES TO BE PRODUCED BY CASTINGS, AND C. INPRESSING SAID FORMS INTO SAID MATERIAL THEREBY CAUSING THAT MATERIAL IN THE AREAS OCCUPIED BY SAID FORMS TO BE DISPLACED AND CAUSING A FLOW OF MATERIAL INTO A PLURALITY OF SAID VOIDS TO OCCUR TO PRODUCE IN UNDISTORTED IMPRINT CONSTITUTING AN EXACT MIRROR IMAGE REPLICA OF THE FIGURES TO BE CAST, SAID PLURALITY OF VOIDS WHICH RECEIVE SAID MATERIAL INCLUDING VOIDS LOCATED OUTSIDE THE AREAS OCCUPIED BY SAID FIGURES. 